1. Field of the Invention
The invention relates in general to a clutch that produces a drive connection between components when their relative rotation is in one direction, and overruns when relative rotation is in the opposite direction. In particular, the invention pertains to using such clutches to provide a reaction to a force that actuates a friction clutch.
2. Description of the Prior Art
Conventional one-way clutches for producing a one-way drive connection between inner and outer races of the clutch include sprags or rollers for releasably driveably connecting the races and the components of a mechanical assembly connected to the races. Such clutches are commonly used in the powertrain or driveline of an automotive vehicle. One-way clutches perform satisfactorily in many cases, but certain applications, such as those in which large magnitudes of torque are transmitted by the clutch, or those that provide only a small space for the clutch, require one-way clutches other than conventional sprag-type or roller-type clutch to meet desire requirements.
Conventional one-way clutch assemblies have at least one sprag or roller, which driveably locks two notched or pocketed races together mutually in one rotary direction and allows the races to rotate freely in the other direction. Rocker and sprag type one-way clutch assemblies can increase the torque capacity for a given package size compared to those of a roller-type clutch, but they are generally limited in torque transmitting capacity by the magnitude of the contact or bearing stresses caused by contact of the rockers or sprags with the races.
Conventional one-way clutches develop relatively large magnitudes of hoop stress in the races when torque is transmitted through the clutch; therefore, the races of conventional one-way clutches are formed of bearing grade steel in order to withstand the operating hoop stress. Because the clutches develop relative low operating hoop stresses in service, those clutch can be formed of powdered metal. Clutches formed for powdered metal potentially can be produced at relative low cost compared to the cost to form and produce a conventional clutch of high grade steel, provided extensive machining is avoided.
A need exits for a low cost, reliable one-way clutch that produces low operating bearing stresses, is able to be formed readily from powdered metal, and can react the actuating force produced in a hydraulically actuated friction brake. The clutch should occupy little space, minimize in-service noise, and require little or no machining. Preferably, the desired clutch should include features that facilitate its assembly in a drive system.